Re: laser technology

From: Nick Schaefer (nicks@hpbsm92.boi.hp.com)
Date: Fri May 23 1997 - 01:56:30 EEST


>
> To all......
>
> What happens to be the real world current laser life for Rp systems: ( I
> know what is promised)
>
> SLA
> SLS
> LOM
>
> Is there data to support laser care such as room temp, turning off-on,
> UPS sytems, etc?

I can only give a short history of my experiences with laser life on our
SLA250..... so here it is:

   During discussions with 3D Systems before purchasing the machine they
   impressed the importance of reasonably stable room temperature and
   also plenty of air flow through the room.

   The room we put it in is temperature controlled around 68 degrees
   +/- 2 and the air changed about every 12 minutes.

   SLA delivered August of 1992 with a Liconix laser with 32mW at the vat.
     The first laser lasted 1299 hours, then the power went to 0mW.

   Replaced with a Omnichrome and new power supply. 36mW at the vat.
        This one died at 1782 hours.

Now I am starting to worry because I had been told that lasers were
lasting ~ 4000 hours and several were lasting as much as 6000 hours. Also
most were being replaced because the power got so low that it was
taking too long to build parts. The impression I had was that we were
about the only ones that were going from ~ 20mW to 0.

Suggestions from 3D were to add a ups.... Done. Didn't really seem to
help laser life but was probably a good idea to have it anyway.
  
  Next laser lasted just beyond the guaranty, ~ 2200 hours

Next suggestion was to build a sheetmetal sheild to cover the laser
housing with about 3 inches of air space between the two. The idea
here was to keep the laser from cooling to quickly after shutdown
since the laser always finished the part build and then would make
a snap sound and go to 0mW power when turning on for the next
build.... Done.

We also quit turning the laser off between builds unless the next build
was going to be more than 3 hours wait.

  This seemed to be helping.

  At around 1500 hours the laser would run for about 20 minutes then
  shut off. It was the power supply this time.
  
  The FE that came to fix it said to block off all the vents in the
  room that were blowing anywhere near the SLA and remove the sheetmetal
  sheild.... Done.

  When the FE left the laser power was at 25mW. The next morning the
  SLA operator said the laser power had dropped to 20mW. When I arrived
  in the SLA room I noticed he had replaced the sheet metal shield so I
  removed it and the laser power went back to 25mW. So it seems there
  is a direct relation between laser temperature and power output.

  Laser power went to 0mW at 5012.4 hours. The laser power was between
  a range of 25 to 19mW from 1500 hours to 5012.

  New laser installed had 36mW at the vat.

  This one died at 4142 hours.

  New laser installed had 34mW at the vat.

  Current hours and power are 1499.6 and 28mW.

It does seem strange to me that all of our lasers have gone from around
20mW to 0. Several people at 3D Systems have said most just get to low
on power to build at a decent rate of speed and are retired.

I would be interested in what others are experiencing too. Also what luck
is being had with the higher power laser (~60mW) for SLA250 and SL5170.

>
> Elaine
>
>
> *******************************************************************
> Opinions, suggestions, and other controversial matter VOID where prohibited.
> ******************************************************************
> Elaine (Persall) Hunt, Director
> Clemson University Laboratory to Advance Industrial Prototyping
> 206 Fluor Daniel Bldg. Clemson, SC 29643-0925
> 864-656-0321 (voice) 864-656-4435 (fax)
> persall@ces.clemson.edu
> http://design.eng.clemson.edu/rp/persall/elaine.html
>
>

--
Regards,

Nick

Nick Schaefer CAD/CAM/RP Specialist Hewlett Packard Boise Site Telnet 396-4884 or (208) 396-4884 E-Mail nicks@boi.hp.com FAX 1-396-2906 URL: http://meweb.boi.hp.com



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